Municipal Wastewater Treatment – RAS

---

INTRODUCTION:

A large U.S. municipal wastewater treatment plant treats 70 MGD through two parallel 35 MGD flow trains.

INVESTIGATION:

The plant receives odor complaints from neighbors, characterized as “canned corn”-like, even when feeding hydrogen peroxide.

• An engineering study identifies the return activated sludge (RAS) as the source.
• The most offensive component is dimethyl sulfide.

IMPLEMENTATION:

975 - UNITED CARUSOL® Liquid Permanganate is injected into the Return Activated Sludge (RAS) line and the odor is eliminated.

• There is a quick dose response when the permanganate is started.
• There is no negative impact on the biological activity in the secondary treatment process.
• Treatment dosage is 8 mg/L, with peak “slug” doses up to 22 mg/L.

RESULTS:

Estimated savings are 50% of the original peroxide costs.